#1 - NoteMesh -http://www.notemesh.com

This is a collaborative wiki style class note taker.  Users can post their lecture notes, or contribute to existing lecture notes.  NoteMesh encourages classmates to collaborate to create a single definitive source for lecture notes.

#2 - Notely - http://www.notely.net/

This powerful application has it all, Calendar, To-do list, homework organizer, course manager, notes, link, contact and file organizer.

#3 - Evernote-  http://evernote.com/

This application allows the user to text, images, and audio with the ability to tag the save file.  Evernote is free to use up 40 MB of data a month.  The application is supported by mobile devices.